Computer Numerical Controlled (CNC) machines are commonly used for machining parts due to their advantages of speed, accuracy, and automation. These machines may perform a variety of functions on a workpiece such as drilling, lathing, milling machines, grinding, polishing, or may be dedicated to a single function. The machines use a variety of tools to perform these functions.
CNC machines use G-codes for controlling the various tools of the CNC machine. Miscellaneous function codes (M-codes) are a subset of the G-codes and used as auxiliary commands, such as for controlling the delivery of coolant to the various tools. There are a limited number of M-codes available, typically around eight or so, which limits the ability to communicate with the machine.
The delivery of lubricant or coolant is very important in machining of parts on the various tools of the CNC machine. High speed machining can create a very high level of friction between parts producing high levels of heat concentrated in small areas of the work surface. This high level of heat can result in warping of the workpiece or even friction welding, reduced machining speeds, and reduced lifetime of the tool. To prevent this, lubrication or coolant is supplied to the work surface of the workpiece to dissipate heat at local hot spots.
Lubricant or coolant may be flooded on to the work surface, but such methods typically use much more lubricant than is necessary and results in higher costs associated with higher volumes of lubricant usage and lubricant disposal and has negative environmental ramifications. More recently, there has been a trend towards using minimum quantity lubrication (MQL) systems for delivery of a smaller quantity of lubrication to a work surface.